Effect of Nitrogen and Cycocel on Nitrogen Content, Remobilization and Use Efficiency in Safflower under Different Planting Densities

To study the effect of cycocel, nitrogen and planting density on nitrogen (N) content, remobilization and use efficiency of Esfahan 14 safflower cultivar, a field experiment was carried out as a factorial split-plot based on randomized complete blocks design with three replications at Research Farm of College of Agriculture, Yasouj University, in summer of 2010. Main plots were the factorial level of N (50, 100 and 150 kg/ha) and level of cycocel (0 and 10- 6 M) and subplots were planting density (20, 25 and 33.3 plants / m2). Results showed that the highest N remobilization (1.21%) was gained from 10-6 M cycocel application and the highest amount of N and planting density. The highest N treatment, along with planting density of 25 plants/m 2, produced the highest seed protein (14%) and aerial N at flowering stage (2.15%). The highest grain yield (3146 kg/ha) and N use efficiency (62.9 kg/kg) was obtained from 10-6 M cycocel, lowest N level and 25 plants/m 2. In general, increasing N application and planting density, with cycocel application, increases shoot N content and remobilization. However, lower amount of N application is associated with higher N use efficiency and seed yield.